Interested in Infrastructure?

The hilly topography in and around Asheville, N.C., makes the city a prime tourist destination. The Blue Ridge Mountains, local waterfalls, hiking trails and scenic vistas bring over 9 million visitors to the area every year.

But the terrain – featuring changes in elevation of 1,000 to 1,500 feet in some places – also presents unique challenges to the Asheville Water Resources Department, especially as the department works to reduce nonrevenue water loss.

With some 50 different pressure zones in its service area, the Water Department is constantly dealing with pumping, valving and storage issues as it strives to deliver a reliable stream of high-quality water to its 56,000 customers on a daily basis.

“Elevation is always a problem here,” says Ivan Thomas, the Water Department’s operations manager. “The pressures amplify water loss. We are looking at ways of reducing pressures [which can reach 400 psi in some places along the system] and are being proactive.”

Through a comprehensive team approach – including a water loss audit program and departmentwide understanding and acceptance of the goals – Asheville has cut those losses from 6 million gallons and approximately $3,600 of lost revenue a day in 2012, to 5.4 million gallons and $2,792 a day in 2014.

Surface water supply

Asheville draws its water from two reservoirs and the Mills River. At the North Fork and Bee Tree reservoirs, treatment facilities use conventional filtration to produce finished water. The Mills River treatment plant uses ozone. Water from the reservoirs flows by gravity some 13 miles to the city, while the Mills River water is pumped. Altogether, the facilities deliver about 20 mgd of high-quality water for Asheville’s residential and commercial customers and for firefighting.

The distribution system consists of 1,600 miles of pipe, ranging in diameter from 2 to 36 inches. Some of the piping is galvanized or cast iron and is more than 100 years old. The city maintains 40 pump stations and 32 ground storage tanks, with a total capacity of 25 million gallons.

The system has 16,000 valves and 7,500 hydrants. Population served is about 125,000.

The Water Department’s 146 employees are in charge of all the treatment facilities and distribution lines, service lines, storage and pumping facilities, hydrants, valves and meters in the system, and are divided into six divisions:

• Customer service – handles all customer calls for the city, although 90 percent relate to water issues. This group also handles billing.

• Administration

It’s a team approach that carries over into the city’s program to reduce nonrevenue water loss.

“You can never involve staff too much in nonrevenue water planning,” says Thomas. “The simplest thought could spark the best idea. We talk about water loss at our monthly and quarterly meetings. All of our projects have a nonrevenue water loss aspect to them.”

Water loss

Asheville’s battle against water loss dates to 2012. In that year, according to Thomas, it became evident that the city was losing a fair amount of nonrevenue water and that it was time to put a program together to address it. “We were still using percentages, which is not a good benchmark for water loss,” Thomas says. “And our water loss was around 30 percent. That number varies among utilities. There’s really no good benchmark.

“We had no proactive leak detection or valve exercise program. We had data for billing, but it had really been a long time since we looked in depth at what was happening. We needed a water audit to really see where we were at.”

The city hired the firm of Cavanaugh – water loss experts with offices in Asheville as well as Winston-Salem and Wilmington, N.C. – to perform a complete benchmark audit. “It was a really good first step,” Thomas says.

The benchmark revealed the water and related revenue loss and ranked Asheville at a 68 on the AWWA water loss scale of 100 for data validity.

With valid data in hand, Thomas and his staff went to work, organizing a full-scale assault on nonrevenue water that included leak detection, valve exercising, meter testing, unbilled customers, pressure reduction and zone metering, among other measures.

“In that first year, we were able to divert two employees from existing positions into full-time leak detection,” Thomas says. “On a map grid, the team ‘listens’ to 6 to 8 miles of pipe a day, using ground-to-machine correlators [L-mic and X-mic from Fluid Conservation Systems]. We have two of them. Unless there’s an emergency, we’re out there [listening] every day. We’ve made pretty good progress.”

Two full-time employees have also been assigned to valve exercising, an activity that the city hadn’t been practicing regularly. Thomas says the valve team now makes sure the utility’s 16,000 valves are turned on and off at regular intervals, so that his crew is confident a valve can be shut off when necessary.

Meter testing

Meter testing is another measure on Asheville’s water loss checklist, as well as systemwide conversion to automated meter reading. Thomas explains that the water loss team is testing the larger meters on the system, with the goal of testing 100 meters per month. “We’re testing all of our 1 1/2-inch meters and larger,” he says. “We have about 3,800 large meters out there, so it’s really important that the accuracy of these meters be right.”

At the same time, the city is converting all of its 56,000 meters to drive-by reading, using Hersey Meters from Mueller Systems. The move, begun in 2008, not only improves meter reading accuracy, but has allowed Asheville to reduce the number of required meter readers from eight to three, with the extra employees now assigned other tasks as part of the water loss team.

The water meters at each of the city’s three treatment plants are also being tested regularly. “We weren’t doing this before, but we need to know what we’re producing compared to what we’re selling,” Thomas says.

The team’s customer service group is performing several important functions as part of the water loss reduction effort. For one thing, Thomas explains, the group reviews unbilled customers – like the city’s unmetered fire lines, where water is used for firefighter training and firefighting but might not be billed. The team then educates users on the nonrevenue water loss issue.

“We’re also using GIS to identify properties where we might have people hooking up to the system without anyone knowing about it,” Thomas says.

The customer service group is also concentrating on stopped meters, investigating if the stop is legitimate, or if water might be flowing but the meter is not recording. “If we see zero consumption we send a technician out to confirm,” Thomas says. “We need to make sure we’re billing and accounting for all our finished water.”

Topography

And then there’s the topography. The pressures needed to move water to higher elevations can exacerbate water leaks. “A small leak at high pressure can result in higher loss and increased property damage,” Thomas explains.

Asheville and its consulting partner Cavanaugh have developed a “pressure zone” plan that divides the overall service area into smaller districts or zones. The approach helps narrow the search for leaks or other causes of water loss.

Using the Water Department’s SCADA and GIS systems, the nonrevenue water loss team is now able to develop an understanding of what’s going on in a particular zone and how many customers there are. A project is underway to meter and monitor all pumping stations for pumping efficiency curves and run times, and how much water is being pumped into the zone versus how much the department is selling. “This can have a huge impact on nonrevenue water loss,” Thomas says. “After the zone meters are installed, we will have a template to guide us on where to be more effective in our water loss efforts.”

Other measures include installing pressure relief valves at some points along the system to reduce pressure, and pre-emptive construction of new pumps and tanks, or new or larger lines. For example, in a zone with one of the more exaggerated elevation drops, a major capital project is designed to add new control valves and another ground storage tank. Thomas says the improvements will reduce pressures in the zone nearly 150 psi while increasing fire flow and firefighting storage.

Pipe replacement is also part of the department’s capital program, especially with the system’s 100-year-old cast iron and galvanized lines. “We replaced about 10 miles of our distribution lines last year,” Thomas says. “We know where we have fire flow issues or low pressures. The galvanized and cast iron pipes break all the time. There are no joint restraints and it is generally an old leaded joint or rusted pipe, and that gets worn down.”

Thomas says the old lines are prioritized on a rating sheet and work gets done on that basis.

Because of the high pressures, ductile iron is the choice for new or replacement lines. The new pipe is installed alongside the older lines, Thomas says, unless utilities interfere. “To avoid that kind of conflict, we’ll dig new trenches,” he says. “We try to stay out of roadways.”

The end game

Taking on nonrevenue water loss has taught the Asheville Water Resources Department several lessons, but Thomas says the most important is team play. “Having everybody on board is the key,” he says. “We have our water loss game plan, and everybody is on the same page.

“We still have a lot of work to do,” he adds. “And we don’t know the full impact of our actions until we implement them.”

Asheville’s objectives are steady improvement and forward movement, along with taking pride in what it has been able to accomplish.

“I’d love to be able to say we’ll be down 3 million gallons a day, but realistically I don’t want to be overzealous,” Thomas says of an overall goal. “We’re implementing best business practices, helping to reduce nonrevenue water, making our system more efficient for us and the ratepayers of Asheville and Henderson County.